Conventionally, vessels having pourers have been used for various use purposes. As a kind of vessel like them, there is known a spout pouch with a pourer (spout) attached to a packaging bag (pouch). In recent years, as a result of widespread proliferation of the spout pouches, various contents have come to be filled in spout pouches.
When the contents to be filled are soy sauce, edible oil, and alcoholic drinks, the contents are preferably prevented from contacting oxygen in the air as much as possible in order to prevent deterioration by oxidation. Consequently, in order not to suck external air directly after pouring a content, a vessel equipped with a check valve in which the check valve is incorporated in the pourer is demanded.
Patent Literature 1 describes the check valve having a mechanism that closes the valve by using a restoring force of an urging member (a coil spring or the like), as the check valve applicable to a vessel equipped with the check valve. In the check valve, a spool (a shaft portion) that is connected to a valve body engages with the urging member. The valve body is urged toward a seat face of a valve seat portion by the urging member, via the spool.
In the check valve of this kind, at the time of pouring a content, the vessel main body such as a packaging bag is pressed by hand. Thereby, the valve body is separated from the valve seat portion against the urging force of the urging member with the internal pressure of the vessel, and the valve is opened. At the time of stopping pouring of the content, compression to the vessel main body is stopped. Thereby, the valve body is seated on the valve seat portion by the restoring force of the urging member, and the valve is closed.